The IOBUFDS_DCIEN (HP I/O banks only) and IOBUFDS_DCIEN_XP5 (XP5IO I/O banks only) primitives allow bidirectional differential buffers with input and termination control. The IOBUFDS_DCIEN UNISIM is shown in the following figure. It has an IBUFDISABLE port that can be used to disable the input buffer during periods that the buffer is not being used. The USE_IBUFDISABLE attribute must be set to TRUE, the IBUFDISABLE port must be controlled, and SIM_DEVICE set to ULTRASCALE for this primitive to have the expected behavior that is specific to the UltraScale architecture. The IOBUFDS_DCIEN primitive also has a DCITERMDISABLE port that can be used to manually disable the optional on-die receiver termination features (uncalibrated or DCI). See DCI in the HP I/O and XP5IO I/O Banks and Uncalibrated Input Termination in HP and HD I/O Banks for more details.
The IOBUFDS_DCIEN primitive can disable the input buffer and force the O output to the internal logic to a logic-Low when the IBUFDISABLE signal is asserted High and the output buffer is 3-stated (T = High). The IOBUFDS_DCIEN_XP5 primitive can disable the input buffer and force the O output to the internal logic to a logic-High when the IBUFDISABLE signal is asserted High and the output buffer is 3-stated (T = High). If the I/O is using an on-die receiver termination feature (uncalibrated or DCI), this primitive disables the termination legs whenever the DCITERMDISABLE signal is asserted High and the output buffer is 3-stated (T = High).
When the output buffer is 3-stated (T = High), the input buffer and any on-die receiver termination (uncalibrated or DCI) are controlled by IBUFDISABLE and DCITERMDISABLE, respectively. When the output buffer is not 3-stated (T = Low), the input buffer and any on-die receiver termination (uncalibrated or DCI) are disabled and force the O output (to the internal logic) to a logic Low. These features can be combined to reduce power whenever the input is idle for a period of time.
Although uncommon, if a design requires an input be constantly enabled while maintaining the ability to dynamically control DCI, this primitive can be used by floating the IBUFDISABLE pin and setting the USE_IBUFDISABLE attribute to FALSE.